This invention relates to an exposure device for intermittently feeding a strip-like article a predetermined amount and sequentially exposing it, and in particular an exposure device having a mechanism for setting the feed of the article.
Generally, an aperture mask (shadow mask) for a color cathode ray tube is manufactured by a photoetching method. The photoetching method broadly comprises four steps: a step for applying a photosensitive coating on each surface of a band iron; a step for exposing each surface of the band iron to print a pattern thereon; a step for developing the pattern on the surface of the band iron; and an etching step. In the exposure step, the pattern on the negative plate is sequentially printed on each surface of the band iron, and a cycle of the feeding of the band iron a predetermined amount, attaching of the negative plate under suction onto each surface of the band iron, exposing the surfaces of the band iron by light sources, and moving of the negative plates away from the band iron are repeated at an interval of 150 to 180 seconds. The feeding of the band iron is effected by winding around a winder the band iron fed through an exposure mechanism from an unwinder on which the band iron is wound.
To intermittently feed the band iron a predetermined amount there will be required a feed setting mechanism adapted to detect the feed of the band iron and move it a predetermined amount.
As the feed mechanism of this type there is known, for example, one in which a detection roller is held in contact with a band iron to cause the former to be rotated according to the movement of the latter, a cam is rotated through an interlocking gear mechanism by the rotation of the detection roller, and a switch is operated through the cam to stop the winding operation of the band iron, thereby attaining the intermittent cyclic movement of the band iron. Where, in this case, it is desired to change the feed of the band iron, a gear in the interlocking gear mechanism is replaced by another gear so that a different gear ratio can be obtained. It is, however, very difficult to effect a gear exchange and it is impossible to change the feed of the band iron into a stepless mode. Furthermore, a feed accuracy of at least .+-.5 mm is merely attained due to the defects, such as backlash etc., of the interlocking gear mechanism per se, thus failing to attain a more accurate feed required.